Nope, you can only track objects with Mocha AE. For Remove & Insert modules you need Mocha Pro
I see.... and I thought I would do my job without spending any more money... hahaha...
Thanks for the tip!
You can track things, create masks, export the masks, remove backgrounds, and do a bunch of really amazing things with the version of Mocha that comes with AE, you just can't drop a clip into the included version of Mocha and render out a composite. There are also other goodies in Mocha Pro.
I'd suggest that you go through a fist full of Mocha tutorials. There are a bunch of good ones on the Imagineer Systems site. Try filtering the results by Mocha AE.
Since you have AE 10.5, you also have access to the Rotobrush tool. Depending on the nature of your shot, it may do the trick.
A word of warning: Rotobrush can't be used intuitively. You need to watch the video tutorials at the very least. You'll find them by going to AE Help, using the search term Rotobrush, and an entry with a name something like Rotobrush Resources should be there.