How can I generate big data sample for Postgresql using generate_series and random?

To insert one million rows into Towns

insert into towns (
    code, article, name, department
)
select
    left(md5(i::text), 10),
    md5(random()::text),
    md5(random()::text),
    left(md5(random()::text), 4)
from generate_series(1, 1000000) s(i)

Since id is a serial it is not necessary to include it.