Any good explanations of pg_send_execute and friends?

Has anyone found anything in their travels around the web?

The manual is okay, but the examples are so simplistic it's difficult
to understand how it should really be used. For example, if I have a
loop of pg_send_execute based INSERT statements inside a transaction*,
and one of them fails, how and when do I check for that (given that
the pg_send_execute is asynchronous)?

* That is:
BEGIN
for (...)
{
  pg_send_execute(...);
}
COMMIT