<img class="thumb" width="200px" height="150px" :src="getThumb(item.type)" />

<script>
...
methods: {
 getThumb(type) {
 let thumb = {
 WMS: require("img/world.jpg"),
 WFS: require("img/wfs.jpg"),
 tool: require("img/tool.jpg")
 };
 return thumb[type];
 }
}
...
</script>

...
 resolve: {
 extensions: ['.js', '.vue', '.json'],
 alias: {
 'vue$': 'vue/dist/vue.esm.js',
 '@': resolve('src'),
 'assets': path.resolve(__dirname, '../src/assets'),
 'img': resolve('static/img'),
 '%': resolve('./static')
 }
 },
...

<img class="thumb" width="200px" height="150px" src="https://www.gxlcms.com/static/img/world.jpg" />