FYI...
Some folks are buying legit 16610 and 16710 inserts on the secondary market (sealed in the Rolex blister, loose, used, new w/o the blister) and the fit seems to be off. The insert just don’t fit into the bezel no matter how much you push with your thumbs (ouch). Sometimes you need extra help like carefully using good plastic pliers. I was able to get many of my inserts to work with ample electrical tape wrapped around my rectangular metal pliers.
Obviously this can make some people to think the insert might be a reproduction despite looking perfect (colors, numbers, rear bezel lips, etc...). Apparently like dial fonts, Rolex does make subtle changes with inserts (not just the front #s).
Take a look at this 2014 topic that helped me. Some really good info in it. In summary, some inserts especially the 16710 Red/ Black seems or be harder to install (mine was new in the blister). I also found new / sealed Root Beers to be difficult.
https://www.rolexforums.com/showthread.php?t=350894
Good luck. Special thanks to @Jocke and @Rikki posting in the topic linked above.