Yes and No... If you are talking about sideskirts then the answer is yes they will fit.. But for front and rear bumpers or lip the answer is no because the Sedan is a bit wider than the Wagon. Theres still some tight Wagon body kits like Dolphin, Liberal etc.
If you're trying to fit aftermarket sideskirts on a non-WRX impreza (like a TS) you need the black plastic stock WRX sideskirts first and put it over the rocker panels because most WRX aftermarket sideskirts are made to fit on top of the stock ones