A flow control insert includes a main body that is shaped as a cylinder, is hollow, and includes an opening at a first end and at a second end, opposite the first end, along an axial length of the cylinder. An outer surface of the main body includes threading to screw into complementary threading on an inner surface of a pipe configured to flow an agent. The flow control insert also includes a diverter within the main body or extending from the first end of the main body. The diverter controls a mass split of the agent or flow energy of the agent flowing in the pipe.