Out of curiosity, how the h*** did you scratch the bezel with the tool when changing the strap? I put the watch face (and bezel) down and manipulate the spring bars from the back. I could see scratching the case back from a slip, but can’t for the life of me see how one would scratch the bezel.
Regarding bezel inserts, don’t buy any of the ones on eBay - they are almost certainly fake, since Omega has never sold inserts separately, just the entire bezel assembly. Depending on when you last had the watch serviced, it might be worth it to have the watch serviced and a new bezel put on. They will also clean up scratches on the bracelet.