The water pump is 16412-73030, and gasket 17331-73430
I would start by taking off the radiator cap, fill the radiator to the top.
Then run it, first look for circulation, and look for bubbles.
If you have no circulation let it run for a bit checking temp of the water, run till warm.
If you still have no circulation you have a bad pump.
Note: This is not 100%, some radiator styles make it really tough to see circulation.
If you have bubbles, smoke puffs, steam puffs, or you see an oil sheen on the water in the radiator, shut it down and pull the head!
If circulation is good, and no bubbles, pull the fan belt and check for smooth rotation of the fan and water pump.