water pump leak!!

hi guys right first of all thanks for the help with the other stuff ive asked about. so far your advice has helped me fix the cruise control got new 18" wheels for it ive ditched the 20" ones and tightened the mass damper back up. Now ive discovered a water leak from the back of the water pump not loosing much water but it needs doing. the question is though the water pump is working perfectly well no nasty noises coming from it and its pumping the water round fine. should i replace the whole pump or just the gasket it appears to be leaking from the top of the pump and creating a little resevoir of water on the right hand side. oh im changing the sepentine belt while its off as well.

Take the pump off, check the impellor is secure, clean the mating faces and repl;ace the gasket!