[Butcher]

That doesn't look much like brass to me, as for corrosion, it depends on the standard potential of the metal, the normal problem is between alu and copper which have opposing potentials - they basically create a battery with the water as the dielectric. The problem is the alu corrodes as part of this. Hard to say what that metal is, silvery metals are pretty common and that could be a plated part. Water wetter should prevent any serious corrosion anyway so it should be fine.