You can easily change the URL of your pages and posts.
Content below courtesy of Wordpress.org's page on Pages.
URLs of Your Pages
WordPress will automatically create a URL part ('slug') for your page as soon as you complete the name of the page/post title.
Changing the URL of Your Pages
To change the URL part (also referred to as 'slug') containing the name of your Page, use the 'Edit' button under the Page title on the Edit screen of the particular Page, accessible from Pages tab of WordPress Administration Panel.