Well, seeing as the stock 06 17" wheels are 7" wide, you have a match there. I believe the offset of the stock wheels is 52 or something close, so a 48 will be fine, as it will allow the wheels to sit a bit farther out. Lastly, the 5x100mm bolt pattern is correct for the 06 WRX.
Everything should be good
One question for you though....Why the heck are you putting stock tires back on aftermarket rims. They absolutely suck. I'm assuming for money reasons, but they are just not a good tire as others have stated many times before. I'd look into something else if I were you.
Hope this helps