Asumption: You use Apache as your web server.
If you already know the page slugs and they won’t change, just add them to your .htaccess
file. It’ll be much faster and less complicated.
Paste the following Redirect
lines at the top of your .htaccess
file.
Redirect 301 /pagetitle/ /service/pagetitle/
Redirect 301 /pagetitle2/ /another-dir/pagetitle2/
# BEGIN WordPress
<IfModule mod_rewrite.c>
....