Hi, water pump housings have troubles even on 08 bikes.
As long as Beta will have stock they will mount the bad ones.
It does not cost so much.
The problem seems to come from the fact that the magnesium (type of steel, sorry I don't know the term in english) is crappy and the coolant gnaws the casing.
I have unmount mine on a 05 model, the housing is bubbly, I don't know if it is the cast, or the wa it is made, but it seems fairly weak.
KR
J