I've been silver soldering ss/brass/cu in all combinations for a while. They all work great for me. Only disadvantage is that solder needs a very close fit. it just won't bridge gaps of more than maybe 0.010".
If I have sloppy fits, I break out the acetylene/oxy and silver braze.
Pump orientation will not affect wear.
The roughly 45deg angle should not give you much increased risk of cavitation either. Should...
The only likely mechanism of cavitation that I can see is that the high point (elevation-wise) in the pump head may now be in the intake line near the...