Various embodiments include methods and apparatus structured to pump material, where such material is difficult to pump. In an embodiment, an apparatus can include an injector device capable of self-injecting material into a high pressure line. The apparatus may include multiple valves to control recharge of material into the injector device and to control reinjection of the material into the high pressure line. In an embodiment at a well site, a portion of fluid being injected into a wellbore can be diverted from one or more high pressure pumps to an injector device, where the diverted portion of the fluid can be used to power the injector device to inject material from a mixing tank to add material to the wellbore in addition to the non-diverted portion of the fluid injected into the wellbore. Additional apparatus, systems, and methods can be implemented in a variety of applications.