Hi Andy.
If it is the outer bearing closest to the pulley you maybe ok. ( not directly lubed by pump ) sitting in a seperate
front housing from main pump body.
If it is an internal bearing then maybe the following may help.
First of all i would replace the bearing in the pump. on doing so, check to make sure all of the old bearing is complete when you remove it, and that it has not broken up.
if it has broken up there is a possibility that some debris might have made it's way into the steering rack.( lets hope not ). There is sometimes a mesh filter on the outlet of the pump that stops any larger parts going round the system. if this is the case then it would be a good idea to change the oil.
When you have changed the pump and refilled the system with oil. jack the front of the vehicle of the ground, start vehicle and turn the steering from lock to lock slowly. once you have done this a couple of times. ( check oil level ) then turn and hold the steering hard on left and the right hand lock for 10 secounds each side and this should remove any air in the system by getting the presure relef valve in the pump to work.
Recheck steering fluid level.
hope this is of some help.
rdgs
Clive