A method of manufacturing a fluidic oscillator insert for use in a subterranean well can include forming the insert with a conical housing engagement surface thereon, and forming at least one fluidic oscillator on a substantially planar surface of the insert. A well tool can include a housing assembly, at least one insert received in the housing assembly, the insert having a fluidic oscillator formed on a first surface thereof, the insert being at least partially secured in the housing assembly by engagement of conical second and third surfaces formed on the insert and housing assembly, and a cover which closes off the first surface on the insert. An insert for use in a well tool can include a conical housing engagement surface, and at least one fluidic oscillator formed on a substantially planar surface. The fluidic oscillator produces oscillations in response to fluid flow through the fluidic oscillator.