Most SEO experts advise that the URL structure for WordPress should utilize the keywords that you are trying to rank for, rather than arbitrary digits or numbers.
For this reason, one of the first things you should do after installing WordPress is to adjust the permalink settings in the admin panel. The default setting uses the WordPress post number, and this should be quickly changed to a custom setting.
Failing to change the permalink structure when you first install WordPress can lead to some problems down the road. If you change it after already publishing some posts, it will cause 404 errors to show up in your Webmaster tools account. Too many of these errors can have an effect on your search rankings.
Most people set the Permalink structure to match the title of the post or page. So a post entitled “how I trained my dog” would have the URL structure of “www.domain.com/how-I-trained-my-dog/”.
Some people choose to remove the stop words, which are simply the shorter words which are not critical keywords, and there are several plugins that will do this for you automatically if you would like.
On this blog, I’ve chosen to use this format, but added the WordPress page ID number at the beginning of the custom Permalink structure. In my mind, this gives me the best of both worlds by including the keywords and also including a numeric identifier that is specific to each post.
There are any number of options you can use for your URL structure in WordPress, but you need to make sure that it is formatted correctly in the perm link administrative settings section of for it to work properly.
You can follow this link to WordPress.org for the custom permalink options available. Just cut and paste your chosen option into the admin settings.