Abstract: An apparatus and method for mixing by producing shear and/or cavitation, and components for the apparatus are disclosed. In one embodiment, the apparatus includes a mixing and/or cavitation chamber with an element such as an orifice component that is located adjacent the entrance of the cavitation chamber. The apparatus may further include a blade, such as a knife-like blade, disposed inside the mixing and/or cavitation chamber opposite the orifice component. In one version of such an embodiment, at least some of the portions of the orifice component surrounding the orifice and/or the blade are made of a material or materials that have a Vickers hardness of greater than or equal to about 20 GPa. A process for mixing by producing shear and/or cavitation in a fluid is also contemplated herein.