I think most molders prefer to put part numbers and such on replaceable inserts, for one reason because they change from time to time. For another reason, they may make similar/ identical parts for different customers in the same mold. And they make make minor variants (e.g. extra boss, etc.) using inserts.
I'm not aware that there is a global standard for such inserts, or for the blanks used to make them, but I'd guess that you could buy semi- standard parts from mold base suppliers.
Mike Halloran
Pembroke Pines, FL, USA