Create custom Language specific Error pages in ASP.Net

Hello Experts,

I would like to know how can i redirect user to error page according to his language.

I have 2 cases:

If the user visit my english website version and type wrong page name i redirect him to 404.aspx (Page not found english text) www.sitename.com/hjhj.aspx

If the user visit my arabic website version and type wrong page name i redirect him to 404.aspx (Page not found arabic text) www.sitename.com/ar/hjhj.aspx

this is web.config 

<customErrors mode="On" defaultRedirect="http503.aspx">
    <error statusCode="404" redirect="http404.aspx"/>
</customErrors>