Having just looked through the link that Mike posted, I would suggest the following:
First, the impellor is sacrificial. Don't try to save it. It's junk!
Second. Drill a series of small holes straight down into the impellor, in a line across it, in an imaginary line through the bearing center. (don't go too deep)( you want to go right through the impellor, just!)
Then increase the drill size and re-drill those holes.(hopefully merging the holes?) The idea is to form a line of weakness across the impellor. Then take a suitable sharpish cold chisel and split the impellor. This approach will take some risk out stuffing your pump housing.
You can then press the bearing out from the back of the pump and lastly you press the bearing from your (well supported) pulley.
On the seals. There is some variation in the componentry. The ones in Hanno's picture have more parts than the ones from James. I think Hanno's kit is earlier and is obviously a British kit. The bearing is the same. Some people have spent big money investing in improved modern made pumps. I'm too tight for that.
The above applies to lots of press assembled water pumps across different manufacturers.