When creating or editing WordPress content you can select specific users by username or by user role who can seethat particular post or page.
User Specific Content is a free WordPress plugin that simply lets you select specific users by user name, or by their role name who can view a specific WordPress post or page. All you need to do is install and activate User SpecificContent. Upon activation you can visit Add New Post page and there you will be seeing a new User Specific ContentBox added as shon in the given screenshot.
Now using this User Specific Content you can select viewer ticking checkboxes of their roles or names listed there. Other than this you can also select whether the content is for only logged-in users or both. The plugin also allows you to add blocked content message which comes visible to blocked users on that specific content.