Will cactus juice deteriorate the internal parts of a vacuum pump such as seals and plastic parts?

No!  Cactus Juice is designed specifically for use under full vacuum.  There is nothing in Cactus Juice that will "boil" or vaporize under full vacuum when using it below the use and storage temperature of 85° F.  Cactus Juice can boil if the temperature of the resin is above 93° F which is outside the maximum use and storage temperate of 85° F to begin with.  Also, a quality vacuum pump does not contain any rubber (or other material) seals that are in contact with the air stream and do not contain any plastic parts in the actual vacuum cartridge.  Some of the cheap import pumps do but even then, Cactus Juice will have no effect on them unless you suck resin into the pump.