Abstract: The cutting head of an abrasivejet cutting system preferably includes a replaceable generally tubular cartridge supporting a waterjet-forming orifice-defining member on one side of a mixing region, and an abrasivejet nozzle positioned on the opposite side of the mixing region in axial alignment with said orifice. The cartridge is formed from a material having tensile strength, yield strength and fatigue strength sufficient to withstand the operating pressure of the cutting system and sufficiently malleable and ductile to form a hard seal with a water-inlet tube to which it is coupled. The mixing region is defined within the cartridge by a layer of another material that is more abrasion-resistant than the cartridge material.