I haven't found an unmarked used pump. New pumps are either unobtainable or priced more than if solid gold. There are some searches going on for compatible rotor sets from other bike brands where these parts are service items (the Honda pumps most only sold complete) but as far as I know nobody has found a drop-in set.
Quite a bit of damage is fine. Particularly the scavenge pump seems to get pitted, and it doesn't seem to matter there. The smaller pressure pump seems less prone but they are always scarred somewhat. Rotor mating face pitting doesn't seem to cause serious problems, outer rotor surface and case surface wear are more serious. If the ends and case surfaces are relatively smooth check the radial clearance (feeler gauge) and end clearance (plastigage) - if they're in spec the pumps should be good to go. Replacing the seals and O-rings is recommended, I think a member here has kits available.
