I suppose you could go down the path of checking clearances and making sure they are within factory spec's. You could argue that this confirms the pump is ok and it probably is.
You have at least bought new gears.
Most people as you have seen above (and including myself), consider the oil pump to be such a major part for a relatively low price (compared to the price of what you pay for rods, pistons etc), that they would replace it with a new one to have that confidence that it is as good as possible. I also do the same with water pumps, its just too difficult to have to change the thing if it starts to leak or drops a bearing.