In plain English
FAR 52.232-24, Prohibition of Assignment of Claims, is a contract clause prescribed at FAR 32.806(b), most recently dated May 2014. The complete official text is reproduced below, verbatim, from GSA's published FAR source files.
Its text contains no sentence requiring insertion into subcontracts; see the flowdown section below for what that does and does not mean.
Does it flow down to subcontracts?
No flowdown mandate found in the clause text
We scanned the full clause text and found no sentence directing the contractor to insert this clause into subcontracts. That is a statement about the text, not legal advice: a prime contractor may still flow terms down contractually, an agency supplement (DFARS, VAAR, …) may add requirements, and clauses listed below (if any) may order this clause into subcontracts from the outside.
Where it's prescribed
As prescribed in 32.806(b), insert the following clause:
Prescribing reference: FAR 32.806(b).
The official text, verbatim
As prescribed in 32.806(b), insert the following clause:
Prohibition of Assignment of Claims (May 2014)
The assignment of claims under the Assignment of Claims Act of 1940 "(31 U.S.C.3727, 41 U.S.C. 6305)" is prohibited for this contract.
(End of clause)