You didn't show us your output module settings.
Here's probably what is going on. First, you are confusing aspect ratio and pixel aspect ratio. Aspect ratio is the ratio of the height of a frame to the widh. Pixel aspect ratio an artificial number that allows you to put fewer pixels into a frame. This lowers the data rate and the resolution. They have nothing to do with each other. Let me clarify.
To save bandwidth non square pixel aspect ratios were invented so that fewer pixels would be required to fill a frame. In the same way an anamorphic lens (cinemascope) squeezes a film image, non square pixels squeeze a digital image into a smaller container. When the non-square format is played back the image is expanded once again so that the distortion caused by squeezing is fixed. This started with widescreen DV formats where all digital video was 720 pixels wide and was carried over to HD because the equipment available at the time was incapable of playing back or recording a full resolution HD frame.
When you are working in a production environment you should always do as much of your work as you can on a square pixel canvas. After Effects and Premiere Pro (and any other video app I've ever used) will automatically fix the distortion in your non-square footage as long as you follow a few simple rules. Make sure the footage is interpreted properly (yours is) and add the footage to the a square pixel composition. Your footage is 1440 pixels wide and 1080 high so it will fit perfectly in a standard 1920 X 1080 frame (composition). Work that way and your rendering problem will be over. Your non square pixel footage would also work perfectly in square pixel comp of any size from 100 X 100 pixels to 3000 X 200. The footage would not fit perfectly in the frame but the footage would not be distorted. You could uniformily scale the footage up or down to fit any sized frame as long as you were working in a square pixel project.
The other thing to consider is that there are only a few devices left that require non square pixels in their delivery format. Everything shown on the web is square pixels. Unless you have a specific need for rendering a 1440 X 1080 file you should be rendering 1920 X 1080 or other square pixel standard size. That's the only way to guarantee you are going to avoid distortion because almost every video player is incapable of un-squeezing the video to remove the distortion. It would be like a movie theater trying to project a cinemascope movie without a cinemascope anamorphic lens on the projector. You would end up with squeezed movies. Check out this frame of a cinemascope movie.
Everything is distorted and can only be fixed by projecting through an anamorphic projection lens.
If I knew the output module settings, the codec you rendered to, and what how you are trying to deliver the final product I could say for sure, but I'd bet that if you just dropped your main comp in a new standard HD comp (same frame rate) that your squeezed video problem would go away.
Perfect, I've started rendering at 1920x1080 and the issue is solved and now I have a better understanding of how it all works. Thank you very much for the help