Oh, yeah. I had an EXTREMELY difficult time getting it out. There was some kind of sealant put on it, and it WOULD. NOT. LET. GO. I even stood on the engine and pulled with all my might. No luck.
What I had to do is hack up the original pump. The pump is aluminum, and the pipe is steel. So, I used a Dremel tool to cut as much of the aluminum away that I could. It takes a careful hand to do it, but it's achievable. If you use this method. you'll see sparks from the cutting blade when you've hit the steel pipe. When you see sparks, don't cut any deeper; move on to a different spot.
Alternately, you could probably use a blowtorch or something else to heat up the water pump housing. I didn't have that handy, nor sure how to use it.
There's a rubber o-ring that goes on the steel pipe, that sits in the hole on the pump. You'll likely damage it, so you should look around for it before you go hacking away at the pipe.
Good luck, let us know how it went.