OMEGA Seamaster Professional 300m replacement bezel advice

Omega only sells the entire bezel and insert, not a separate insert, so beware of sellers selling an insert only. And Omega will only sell to watchmakers with an Omega parts account. So, to get a new bezel, you will either need to find a watchmaker with a parts account who will order one for you and put it on, or you will need to send it to an Omega service center and they can put one on. Considering you just purchased your watch and it has an unknown service history, I’d just send it to Omega for a complete service and ask that they put on a new bezel. They would also likely want to replace those faded sundial hands as well.

The only other option is to hunt around for a used bezel on forums or EBay that is in better shape. But that will likely be more frustrating than it is worth in terms of savings.