A downhole pump used for a reciprocating pump system includes a barrel coupling to a tubing string and having a standing valve and includes a plunger coupling to a rod string and having a traveling valve. One or both of the valves can include an assembly comprising a housing, an insert, a ball, and a seat. The insert allowing for flow therethrough defines a ball stop at one end has a ball passage at the other end. The insert positions in flow passage of the housing, and one of the ends engages a shoulder in the passage. The insert is secured in the flow passage with metallic material metallurgically affixed between at least a portion of the insert and the flow passage. For example, brazing material can be brazed at the end of the insert to metallurgically affix the insert in the passage. The ball is positioned in the insert, and the seat is positioned adjacent an end of the insert. The assembly is then incorporated into components of the pump.