You can Use Title module to restrict changes on Title field. You could also try the WikiTools module for Node Title restrictions.

Here is one WikiTools module feature

Move Protection: Disallow change of node titles for users without administer nodes permission.

As @iain maitland suggested you can give permissions to roles for URL Aliases.

You can Use Title module to restrict changes on Title field. You could also try the WikiTools module for Node Title restrictions.

Here is one of the WikiTools module feature

Move Protection: Disallow change of node titles for users without administer nodes permission.

As @iain maitland suggested you can give permissions to roles for URL Aliases.