Since you were new here and since the issue sounded like the typical ones we get here, the FAQs were an appropriate first reply - you may wish to read them since they contain a lot more than the typical information. Also, your posts have been moved out of the BTV 6131 thread, since your issue has nothing to do with a BTV 6131, even if your problem is similar to the one posted there.
The big issue for me is that using the zoom/wide function on the Insignia seems to look okay, but it does crop the picture on the edges a bit
Overscan on TVs is normal, sorry to direct you to another FAQ, but check out the following one on Overscan.
FAQ - On Overscan
With most TVs, unless you're on a pixel for pixel mode (which the Insignia may not have), there will be some
image missing on the sides (and top/bottom) - typically 2-3% on most new TVs. Of course, zooming a 4:3 image will cut off the tops/bottoms. As mentioned by others, Insignia may have more overscan than some other TVs.
We need to understand what programming/source you're watching since, as I mentioned earlier, there is lots of programming where black bars are perfectly normal, as indicated in the FAQ, but where stretching/zooming will result in distorted images, minor loss of image, or major loss of image, depending on the stretch mode(s) invoked by the various devices involved.