Downhole friction reduction systems having a flexible agitator

An agitator deployable in a wellbore, comprising:

• a housing comprising a central axis and a central passage;
• a valve disposed in the housing and comprising a first valve body having a first contact face and a second valve body permitted to rotate relative to the first valve body and having a second contact face configured to contact the first contact face;
• a first valve adapter coupled to the housing and which comprises a first receptacle which receives at least a portion of the first valve body to couple the first valve adapter to the first valve body;
• and
• a flexible valve seat positioned in the first receptacle of the first valve adapter between the first valve body and the first valve adapter and wherein the flexible valve seat comprises a body formed from a first material having a first hardness and a spacer ring embedded in the body of the flexible valve seat that is formed from a second material having a second hardness that is greater than the first hardness.

An agitator deployable in a wellbore, comprising:

• a housing comprising a central axis and a central passage;
• a valve disposed in the housing and comprising a first valve body having a first contact face and a second valve body permitted to rotate relative to the first valve body and having a second contact face configured to contact the first contact face;
• a first valve adapter coupled to the housing and which comprises a first receptacle which receives at least a portion of the first valve body to couple the first valve adapter to the first valve body, wherein the first receptacle comprises a cylindrical inner surface and an annular shoulder projecting radially inwards from the cylindrical inner surface;
• and
• a flexible valve seat positioned in the first receptacle of the first valve adapter entirely between a longitudinal end of the first valve body and the annular shoulder of the first receptacle.