So I have stripped the water pump.
The brass bush was stuck hard on the water pump shaft. I had to damage it getting it off. Should the bush be solid in the pump housing with the shaft rotating inside the bush? I am assuming so or is it the other way round?
I have another bush on order but would be good to know.
The surface of the pump housing looks OK, I will gently sand off any rough edges but there is no corrosion like the other parts had.
I think the the water was being spun around the outer of the brass bush and pumped out of the oil filler 😕