PostgreSQL ERROR: INSERT has more target columns than expressions, when it doesn't

Remove the extra () :

INSERT INTO parts_finishing 
(
 id_part, id_finish, id_metal, id_description, 
 date, inside_hours_k, inside_rate, outside_material
) VALUES 
  ('1013', '6', '30', '1', NOW(), '0', '0', '22.43')
, ('1013', '6', '30', '2', NOW(), '0', '0', '32.45')
  ;

I had a similar problem when using SQL string composition with psycopg2 in Python, but the problem was slightly different. I was missing a comma after one of the fields.

INSERT INTO parts_finishing
(id_part, id_finish, id_metal)
VALUES (
    %(id_part)s <-------------------- missing comma
    %(id_finish)s,
    %(id_metal)s
);

This caused psycopg2 to yield this error:

ERROR: INSERT has more target columns than expressions.

This happened to me in a large insert, everything was ok (comma-wise), it took me a while to notice I was inserting in the wrong table of course the DB does not know your intentions. Copy-paste is the root of all evil ... :-)