you might need another differential/axles, depends on how you do it. and of course, you'll need new rotors irregardless.
since you have a 05 wrx with 5x100, you could buy a spare set of knuckles (the entire unit that the axle passes through, holds the hub and bearing, and the brakes attach to) or remove yours, then have the hub (where the studs pass through) redrilled for 5x114.3 bolt circle then press your studs back in. that would be acceptable on the front, and on the rear you'd have to have your hub redrilled, if possible, to a 5x114.3 pattern and move the studs, or else swap to a different axle/differential setup to utilize R180 axles and hubs (as mentioned above and below by other posters). Lastly you'll have to see if there a a rotor out there that will match your WRX size, and uses 5x114.3 (anyone know of an oem one?), or else have your existing ones redrilled too.
You could see if 6gun could do a run for ya of std. WRX hubs redrilled with the 5x114.3 bolt circle and then just have all your hubs and bearings swapped at once. Again, still have to locate/redrill rotors. Cost would be those 4 hubs, plus 4 bearings and seals, plus rotors. Not 100% sure if the WRX hubs are capable of this, but i would imagine if 5x114.3 hubs can be redrilled to 5x100, then the opposite can be done.