Answering your question, there are multiple tutorials over the network about performing simulations for centrifugal pumps and turbomachinery in general: The step-wise procedure for pumps will have some particularities like mesh refinements (near the tips and gaps) and the setup for the simulation (steady or transient methods, frozen rotor or stage methods, etc).  There are tutorials that can give you a first insight how to properly "start" a simulation, concepts and some tips. The first link of this answer takes you to a popular CFD website, particularly to the section of "Best practice guidelines for turbomachinery CFD" (like a way of a tutorial).

The next step would be looking at "other companies" documented (and available) experiences, they would provide you the more effective ways to perform these simulations. The second link of this answer takes you to the CD-Adapco website, particularly to a playback of an online-conference that they had recently, showing how a company dealt with simulations of different kinds of pumps.

I hope this will help in your research.

http://www.cfd-online.com/Wiki/Best_practice_guidelines_for_turbomachinery_CFD

http://www.cd-adapco.com/webinar/discovering-better-pumps-faster-through-full-fidelity-cfd-simulations

see this video

https://www.youtube.com/watch?v=dalhTs4-0-c