Don't export a Premiere Pro project--Premiere doesn't do Photoshop 3D. Instead, send your AE comp to the Render Queue and render out a flattened movie file. This will import into Premiere.
You might also be able to use Dynamic Link if you have the Production Premium bundle or Master Collection bundle. You can just drag your AE comp into Premiere, and a link will be established. Note that you will probably not get real-time performance with a 3D object using Dynamic Link; the rendered file above will likely provide better results.